The US Environmental Protection Agency (EPA) plans to propose new targets for the final three years of the US Renewable Fuel Standard (RFS) which are closer to current standards than the targets set by Congress in 2007, according to sources quoted by Reuters.

The possible changes to the RFS could set off tensions between corn growers, who would like the highest possible targets to spur investment, and petroleum producers who desire the smallest to reduce costs, the 20 November Reuters report said.

The RFS was introduced to wean the USA off of fossil fuels and will expire in 2022. Refiners are required to blend biofuels into petrol and diesel each year or purchase blending credits from companies that do.

Oil companies say the policy is expensive and has fallen short of targets.

Although the target for 2022 was 36bn gallons (164bn litres) of biofuel, only about 20bn gallons (91bn litres) was produced in 2018, the Reuters report said.

“We are going to ask and we expect to see lower volumes across the board,” said Derrick Morgan, a lobbyist for the American Fuel and Petrochemical Manufacturers.

Biofuel supporters said the targets should remain high to encourage companies to keep investing in new plants and technology.

Growth Energy chief executive Emily Skor said: “Our goal is simple: to keep moving the RFS forward, not backward.”

An EPA official confirmed the agency was working on a reset proposal and planned to finalise plans by November 2019.